Carbon-ceramic brake discs and processes for producing them are known from the patent literature, for example from EP 0 797 555 A1. This document describes how separately manufactured core bodies and friction bodies are joined together with a bonding layer containing silicon carbide. Infiltration with silicon can be carried out separately for each body, and the carbon-ceramic brake disc is produced by placing a siliconised core body and at least one siliconised friction body on top of one another and infiltrating liquid silicon into the gap between the bodies. The disadvantage of this process is that a bonding layer is formed between the friction layer and the core body which consists largely of silicon. This layer has a lower strength than the fibre-reinforced ceramic phase.
A further, improved process is known from DE 100 66 044 A1 wherein a carbon-ceramic brake disc comprising a core body and at least one separate friction layer is produced by first separately manufacturing preforms for the friction layer, placing these preforms in a so-called master mould for the core body and filling the master mould with a material for the core body and producing from this composite the preform for the friction body, which is then pyrolysed and infiltrated with silicon.
This process does not require a specially produced bonding layer between the core and friction bodies. Equally, only one siliconisation is required, namely that of the composite comprising the core and friction bodies. In practice, however, it has been found that this process presents disadvantages. Since the friction layer is markedly thinner than the core body (approx. 0.5 mm to 1.5 mm as compared with approx. 20 mm to approx. 40 mm), high losses are complained of when handling the brittle carbonised preforms for the friction layer, despite special care and attention.
The object of the invention is therefore to provide an improved process for producing carbon-ceramic brake discs, wherein handling is simplified and material loss is reduced.
This object has been achieved by pressing onto a prefabricated carbonised core body a deformable material which after the subsequent process steps forms the friction layer, and the press-moulded body formed in this way is carbonised and then siliconised.